As the interaction between the combustor and the turbine in the aero-engine continues to increase,the film cooling design considering the combustor swirling outflow has become the research focus.The swirling inflow an...As the interaction between the combustor and the turbine in the aero-engine continues to increase,the film cooling design considering the combustor swirling outflow has become the research focus.The swirling inflow and high-temperature gas first affect the vane leading edge(LE).However,no practical improved solution for the LE cooling design has been proposed considering the combustor swirling outflow.In this paper,the improved scheme of showerhead cooling is carried out around the two ways of adopting the laid-back-fan-shaped hole and reducing the coolant outflow angle.The film cooling effectiveness(η) and the coolant flow state are obtained by PSP(pressure-sensitive-paint) and numerical simulation methods,respectively.The research results show that the swirling inflow increases the film distribution inhomogeneity by imposing the radial pressure gradient on the vane to make the film excessively gather in some positions.The showerhead film cooling adopts the laid-back-fan-shaped hole to reduce the momentum when the coolant flows out.Although this cooling scheme improves the film attachment and increases the surface-averaged film cooling effectiveness(η_(sur)) by as much as15.4%,the film distribution inhomogeneity increases.After reducing the coolant outlet angle,the wall-tangential velocity of the coolant increases,and the wall-normal velocity decreases.Under the swirl intake condition,both ηand the film distribution uniformity are significantly increased,and the growth of η_(sur) is up to 16.5%.This paper investigates two improved schemes to improve the showerhead cooling under the swirl intake condition to provide a reference for the vane cooling design.展开更多
An upstream coolant injection that is different from the known leakage flow was introduced to protect the turbine endwall.This coolant is ejected tangentially from a row of cylindrical holes situated at the side of a ...An upstream coolant injection that is different from the known leakage flow was introduced to protect the turbine endwall.This coolant is ejected tangentially from a row of cylindrical holes situated at the side of a backward-facing step.In this experiment,the effects of mass flow ratio and leakage slot width on the endwall heat transfer characteristics were investigated.The dimensionless heat transfer coefficient(Nu)and adiabatic film cooling effectiveness(η)on an axisymmetric turbine endwall were measured by the stable-state thermochromic liquid crystal(TLC)technique and the pressure sensitive paint(PSP)technique,respectively.Three mass flow ratios(MFR)of 0.64%,0.85%,and 1.07%,as well as two leakage slot widths(W)of 3.93 mm,and 7.86 mm were considered.Results indicate that the injection film suppresses the strength of the passage vortex,which leads to the coolant covering almost the entire endwall.This result is more evident for the higher MFR cases,meanwhile,the corresponding averaged film cooling effectiveness is increased with the enhancement of the MFR.However,the case with a higher MFR produces a higher heat transfer coefficient distribution,especially in the region close to the leakage slot edge.Besides,when the W is lower,the endwall presents a higherηand a lower Nu for all the cases,which can guide the optimal design of the endwall.展开更多
By investigating heat transfer and flow structures of dimples,orthogonal ribs,and V-shaped ribs in the impingement/effusion cooling,the article is dedicated to selecting a best-performing internal cooling structure fo...By investigating heat transfer and flow structures of dimples,orthogonal ribs,and V-shaped ribs in the impingement/effusion cooling,the article is dedicated to selecting a best-performing internal cooling structure for a turbine vane.The overall cooling effectiveness and coolant consumption are adopted to evaluate the cooling performance.To analyze the influence of structural modification,the flow field is investigated on chordwise/spanwise sections and the target surface.The blockage effect on crossflow can protect jet flow,resulting in higher heat transfer performance of the target surface.Ribs own a stronger blockage effect than dimples.Compared with the blockage effect,the influence of the rib shape is negligible.By installing dimples between ribs,heat transfer is augmented further.The introduction of ribs/dimples leads to higher discharge coefficients of jet nozzles but lower discharge coefficients of film holes.Thus,the film cooling deteriorates.Meanwhile,the installation of the ribs and dimples decreases total coolant consumption.The effect of ribs/dimples on heat transfer and effusion condition of internal and external cooling is analyzed.The best-performing cooling structure is the target surface with dimples and orthogonal ribs,which decreases the wall temperature and coolant consumption by 14.57-28.03 K and 1.19%-1.81%respectively.This article concludes the flow mechanism for dimples and influence factors on the cooling performance,which may serve as guidance for the turbine vane design.展开更多
The secondary flow originated from the inherent pressure gradient inside the vane cascade has a strong impact on the endwall cooling performance as the crossflow sweeps the upstream coolant jet towards the suction sid...The secondary flow originated from the inherent pressure gradient inside the vane cascade has a strong impact on the endwall cooling performance as the crossflow sweeps the upstream coolant jet towards the suction side,resulting in intensifying thermal load near the pressure side endwall.Hence a novel ribbed-endwall is introduced to suppress passage crossflow.The effects of the mass flow ratio and the rib layout were examined using numerical simulations by solving the three-dimensional Reynolds-averaged Navier-Stokes(RANS)equations with the shear stress transport(SST)k-ωturbulence model.The results indicate that the ribs effectively prevent the coolant migrating from the pressure side to the suction side,helping the coolant jet to spread along the lateral orientation.Therefore,the endwall adiabatic film cooling effectiveness is substantially improved.The maximum cooling effectiveness is achieved for the case with three-ribs when the height of the rib equals one hole diameter among all cases.The area-averaged adiabatic cooling effectiveness is enhanced by 31.6%relative to the flat endwall when the mass flow ratio of coolant to mainstream equals to 0.52%.More importantly,the ribbed-endwall obtains a relatively lower level of aerodynamic loss owing to the reduced lateral migration inside the vane cascade.展开更多
Ceramic matrix composite(CMC),with higher thermal limit and lower density relative to the superalloy,is regarded as the most important structural material for modern gas turbine engines.However,the anisotropic thermal...Ceramic matrix composite(CMC),with higher thermal limit and lower density relative to the superalloy,is regarded as the most important structural material for modern gas turbine engines.However,the anisotropic thermal conductivities caused by the weave patterns totally change the thermal conduction performance inside the solid domain.Therefore,the present study aims to use the infrared thermographic to measure the SiC/SiC composite platform with staggered effusion holes along with the superalloy platform.CMC platform is prepared by 2-D plain weave braid structure with chemical vapor infiltration(CVI)process.The temperature of mainstream is 900 K to match the real mainstream to coolant temperature ratio(T_(g)/T_(c)=1.5,2.1).The experimental was conducted with seven mass flow ratios(MFR=1.5%-4.5%).The results indicate that the thermal conductivity along the thickness direction is of great importance for the CMC platform.The superalloy platform obtains higher level of overall cooling effectiveness than CMC at T_(g)/T_(c)=1.5.However,the CMC platform achieves greater overall cooling effectiveness relative to superalloy at T_(g)/T_(c)=2.1.In addition,CMC platform presents enhanced uniformity of overall cooling effectiveness due to the larger in-plane thermal conductivity.展开更多
For unshrouded blade tip,the high-temperature gas flows through the tip clearance by force of the lateral pressure difference.Thereby,the blade tip endures increasing thermal load.Furthermore,the conventional blade ti...For unshrouded blade tip,the high-temperature gas flows through the tip clearance by force of the lateral pressure difference.Thereby,the blade tip endures increasing thermal load.Furthermore,the conventional blade tip treatment cannot continuously provide protection for the deteriorating service environment.In the present study,aerothermal characteristics of the squealer blade tip with staggered ribs,partial squealer rim and different partial squealer rim thickness were investigated to explore the influences of ribbed-cavity tip on the tip heat transfer,leakage flow and turbine stage efficiency.The numerical results indicate that the ribbed-cavity tips are beneficial for the reduction of the blade tip thermal load and leakage flow.Among the present six blade tip designs,the minimal area-averaged heat transfer coefficient is obtained by the case with the staggered ribs and a deeper squealer rim,which is reduced by 31.41%relative to the squealer tip.Plus,the blade tip modification closer to leading edge or tip mid-chord region performs better than trailing edge in reducing the tip leakage flow.展开更多
基金financial support from the National Natural Science Foundation of China (Grant No.U2241268)the Natural Science Foundation of Hunan Province (Grant No.2021JJ40646)+1 种基金the National Science and Technology Major Project(Grant No.J2019-Ⅲ-0019-0063)the Innovation Capacity Support Plan in Shaanxi Province of China (Grant No.2023-CX-TD-19)。
文摘As the interaction between the combustor and the turbine in the aero-engine continues to increase,the film cooling design considering the combustor swirling outflow has become the research focus.The swirling inflow and high-temperature gas first affect the vane leading edge(LE).However,no practical improved solution for the LE cooling design has been proposed considering the combustor swirling outflow.In this paper,the improved scheme of showerhead cooling is carried out around the two ways of adopting the laid-back-fan-shaped hole and reducing the coolant outflow angle.The film cooling effectiveness(η) and the coolant flow state are obtained by PSP(pressure-sensitive-paint) and numerical simulation methods,respectively.The research results show that the swirling inflow increases the film distribution inhomogeneity by imposing the radial pressure gradient on the vane to make the film excessively gather in some positions.The showerhead film cooling adopts the laid-back-fan-shaped hole to reduce the momentum when the coolant flows out.Although this cooling scheme improves the film attachment and increases the surface-averaged film cooling effectiveness(η_(sur)) by as much as15.4%,the film distribution inhomogeneity increases.After reducing the coolant outlet angle,the wall-tangential velocity of the coolant increases,and the wall-normal velocity decreases.Under the swirl intake condition,both ηand the film distribution uniformity are significantly increased,and the growth of η_(sur) is up to 16.5%.This paper investigates two improved schemes to improve the showerhead cooling under the swirl intake condition to provide a reference for the vane cooling design.
基金the financial support from the National Natural Science Foundation of China(Grant No.U2241268)the National Science and Technology Major Project(Grant No.J2019-Ⅲ-0019-0063)。
文摘An upstream coolant injection that is different from the known leakage flow was introduced to protect the turbine endwall.This coolant is ejected tangentially from a row of cylindrical holes situated at the side of a backward-facing step.In this experiment,the effects of mass flow ratio and leakage slot width on the endwall heat transfer characteristics were investigated.The dimensionless heat transfer coefficient(Nu)and adiabatic film cooling effectiveness(η)on an axisymmetric turbine endwall were measured by the stable-state thermochromic liquid crystal(TLC)technique and the pressure sensitive paint(PSP)technique,respectively.Three mass flow ratios(MFR)of 0.64%,0.85%,and 1.07%,as well as two leakage slot widths(W)of 3.93 mm,and 7.86 mm were considered.Results indicate that the injection film suppresses the strength of the passage vortex,which leads to the coolant covering almost the entire endwall.This result is more evident for the higher MFR cases,meanwhile,the corresponding averaged film cooling effectiveness is increased with the enhancement of the MFR.However,the case with a higher MFR produces a higher heat transfer coefficient distribution,especially in the region close to the leakage slot edge.Besides,when the W is lower,the endwall presents a higherηand a lower Nu for all the cases,which can guide the optimal design of the endwall.
基金This study is financially supported by the National Science and Technology Major Project(2017-III-0003-0027).
文摘By investigating heat transfer and flow structures of dimples,orthogonal ribs,and V-shaped ribs in the impingement/effusion cooling,the article is dedicated to selecting a best-performing internal cooling structure for a turbine vane.The overall cooling effectiveness and coolant consumption are adopted to evaluate the cooling performance.To analyze the influence of structural modification,the flow field is investigated on chordwise/spanwise sections and the target surface.The blockage effect on crossflow can protect jet flow,resulting in higher heat transfer performance of the target surface.Ribs own a stronger blockage effect than dimples.Compared with the blockage effect,the influence of the rib shape is negligible.By installing dimples between ribs,heat transfer is augmented further.The introduction of ribs/dimples leads to higher discharge coefficients of jet nozzles but lower discharge coefficients of film holes.Thus,the film cooling deteriorates.Meanwhile,the installation of the ribs and dimples decreases total coolant consumption.The effect of ribs/dimples on heat transfer and effusion condition of internal and external cooling is analyzed.The best-performing cooling structure is the target surface with dimples and orthogonal ribs,which decreases the wall temperature and coolant consumption by 14.57-28.03 K and 1.19%-1.81%respectively.This article concludes the flow mechanism for dimples and influence factors on the cooling performance,which may serve as guidance for the turbine vane design.
基金the support of National Natural Science Foundation of China(No.52006178)National Key R&D Program of China(No.Y2019-Ⅷ-0007-0168)+3 种基金the Fundamental Research Funds for the Central Universitiesthe Innovation Capacity Support Plan in Shaanxi Province of China(Grant No.2023-CX-TD-19)the Swedish Research Council(VR)the Swedish National Energy Agency(EM).
文摘The secondary flow originated from the inherent pressure gradient inside the vane cascade has a strong impact on the endwall cooling performance as the crossflow sweeps the upstream coolant jet towards the suction side,resulting in intensifying thermal load near the pressure side endwall.Hence a novel ribbed-endwall is introduced to suppress passage crossflow.The effects of the mass flow ratio and the rib layout were examined using numerical simulations by solving the three-dimensional Reynolds-averaged Navier-Stokes(RANS)equations with the shear stress transport(SST)k-ωturbulence model.The results indicate that the ribs effectively prevent the coolant migrating from the pressure side to the suction side,helping the coolant jet to spread along the lateral orientation.Therefore,the endwall adiabatic film cooling effectiveness is substantially improved.The maximum cooling effectiveness is achieved for the case with three-ribs when the height of the rib equals one hole diameter among all cases.The area-averaged adiabatic cooling effectiveness is enhanced by 31.6%relative to the flat endwall when the mass flow ratio of coolant to mainstream equals to 0.52%.More importantly,the ribbed-endwall obtains a relatively lower level of aerodynamic loss owing to the reduced lateral migration inside the vane cascade.
基金support of National Natural Science Foundation of China(No.52006178)National Key R&D Program of China(No.Y2019-Ⅷ-0007-0168)+1 种基金the Fundamental Research Funds for the Central Universitiesthe Innovation Capacity Support Plan in Shaanxi Province of China(Grant No.2023-CX-TD-19)。
文摘Ceramic matrix composite(CMC),with higher thermal limit and lower density relative to the superalloy,is regarded as the most important structural material for modern gas turbine engines.However,the anisotropic thermal conductivities caused by the weave patterns totally change the thermal conduction performance inside the solid domain.Therefore,the present study aims to use the infrared thermographic to measure the SiC/SiC composite platform with staggered effusion holes along with the superalloy platform.CMC platform is prepared by 2-D plain weave braid structure with chemical vapor infiltration(CVI)process.The temperature of mainstream is 900 K to match the real mainstream to coolant temperature ratio(T_(g)/T_(c)=1.5,2.1).The experimental was conducted with seven mass flow ratios(MFR=1.5%-4.5%).The results indicate that the thermal conductivity along the thickness direction is of great importance for the CMC platform.The superalloy platform obtains higher level of overall cooling effectiveness than CMC at T_(g)/T_(c)=1.5.However,the CMC platform achieves greater overall cooling effectiveness relative to superalloy at T_(g)/T_(c)=2.1.In addition,CMC platform presents enhanced uniformity of overall cooling effectiveness due to the larger in-plane thermal conductivity.
基金the support of National Natural Science Foundation of China(No.52006178,51936008)National Key R&D Program of China(No.Y2019-Ⅷ-0007-0168)+1 种基金the Fundamental Research Funds for the Central Universitiesthe Innovation Capacity Support Plan in Shaanxi Province of China(Grant No.2023-CX-TD-19)。
文摘For unshrouded blade tip,the high-temperature gas flows through the tip clearance by force of the lateral pressure difference.Thereby,the blade tip endures increasing thermal load.Furthermore,the conventional blade tip treatment cannot continuously provide protection for the deteriorating service environment.In the present study,aerothermal characteristics of the squealer blade tip with staggered ribs,partial squealer rim and different partial squealer rim thickness were investigated to explore the influences of ribbed-cavity tip on the tip heat transfer,leakage flow and turbine stage efficiency.The numerical results indicate that the ribbed-cavity tips are beneficial for the reduction of the blade tip thermal load and leakage flow.Among the present six blade tip designs,the minimal area-averaged heat transfer coefficient is obtained by the case with the staggered ribs and a deeper squealer rim,which is reduced by 31.41%relative to the squealer tip.Plus,the blade tip modification closer to leading edge or tip mid-chord region performs better than trailing edge in reducing the tip leakage flow.
